As decontamination using hydrogen peroxide vapor, there are a wet type decontamination (wet method) in which hydrogen peroxide vapor supplied to a decontamination target room is caused to be condensed inside the room and a dry type decontamination (dry method) in which hydrogen peroxide vapor supplied to a decontamination target room is allowed to exist as it is in the form of vapor phase without being condensed.
And, with the wet type decontamination as compared with the dry type decontamination, high decontamination effect can be achieved even in a shorter period. On the other hand, the wet type decontamination can not be used in a situation where the condensate of hydrogen peroxide vapor gives an adverse effect to indoor substance, such as causing chemical or physical alternation thereof.
Conversely, the dry type decontamination method provides only lower decontamination effect than the wet type. And, because of this, the former requires a longer decontamination period, but provides the advantage of giving less adverse effect to indoor substance.
Regarding such decontamination using hydrogen peroxide vapor as above, Patent Document 1 (in particular, claim 1 and paragraphs 0066 through 0067) discloses a dry type decontamination method comprising monitoring indoor condensation of hydrogen peroxide vapor by a condensation sensor, specifying, based on monitoring information, the concentration of the hydrogen peroxide indoors when indoor condensation of hydrogen peroxide vapor has vanished and decontaminating the indoor under the specified concentration condition (Prior Art 1).
Further, this Patent Document 1 (in particular, paragraph 0009) discloses another dry type decontamination method comprising specifying a desired concentration of the hydrogen peroxide present indoors in a range where no indoor condensation of hydrogen peroxide vapor will occur, in the course of progressively increasing the indoor hydrogen peroxide concentration and decontaminating the room interior under this specified concentration condition (Prior Art 2).
On the other hand, Patent Document 2 (in particular, paragraph 0067) discloses a wet type decontamination method comprising monitoring indoor condensation amount of hydrogen peroxide vapor by a condensation sensor and adjusting the amount of hydrogen peroxide vapor to be supplied to the room interior based on the monitoring information (Prior Art 3).